In 731 Blood Tests, No Trace Of West Nile Virus

Blood tests taken last fall of more than 700 residents in Stamford and Greenwich failed to turn up any trace of West Nile virus, despite the large number of infected birds found in the area last year.

State officials Thursday said the lack of human infections supported their policy not to spray pesticides, even in areas where the virus was found in large numbers of birds or in pools of trapped non-human-biting mosquitoes.

``What it shows was that we did the right thing by not jumping the gun and starting to spray,'' said Theodore Andreadis, chief entomologist at the Connecticut Agricultural Experiment Station. ``We'll use the data to modify our response plans for this year.''

Fairfield County had the highest number of infected birds and non-human-biting mosquitoes in Connecticut, which made it the epicenter of viral activity in the state last year, the second season the virus has been active in the Western Hemisphere.

But Connecticut had no serious cases of human infections of West Nile, which in rare severe cases can cause encephalitis, a potentially lethal inflammation of the brain.

Officials at the federal Centers for Disease Control and Prevention had speculated that many people in areas of high viral activity such as Stamford and Greenwich may have become infected but had not shown any serious symptoms, which is what happened in areas of Queens, N.Y., during the 1999 outbreak.

Other blood tests conducted by the CDC this fall did find four infected people in Staten Island, N.Y., the hardest-hit area of the country in the 2000 outbreak, when 10 residents were hospitalized with infections. The CDC estimated that only about half of 1 percent of the population, or about 1,574 people, had been infected on Staten Island.

Similar blood tests in Suffolk County, on Long Island, found only one case. And no cases were found among 731 residents living near the Stamford-Greenwich line.

Even so, Connecticut officials stressed that they could not rule out that a few people not tested might have been infected with West Nile.

Andreadis said the blood tests help confirm that human-biting mosquitoes must become infected with the virus before the virus can be transmitted to humans. Last year, the state's mosquito-trapping program found only two groups of human-biting mosquitoes that were infected with the virus.

Andreadis and state health officials said researchers are still analyzing data to determine the best ways to respond to the virus.

For instance, some research from New York suggests that in areas in which human cases were discovered, there were also high concentrations of dead birds, Andreadis said.

The only confirmed human case of West Nile virus in Connecticut involved a Norwalk woman, who tested positive for the virus after experiencing headaches last summer.

While the risk to humans was small, at least last year, West Nile has a firm foothold in the region and will have to be watched closely, officials agreed.

``It's almost a given it will be back this year,'' Andreadis said.

``It's not time to be complacent,'' said Dr. Matthew Cartter, epidemiology program coordinator for the state Department of Public Health. ``We can't say the health risk will be as low in 2001 as it was in 2000.''